This invention is directed to pedaled propulsion systems of the type described in my earlier U.S. Pat. No. 5,335,927, which is incorporated by reference. The invention concerns a drive mechanism for a pedaled vehicle having a rotary drive, e.g., a bicycle whose rear wheel is driven by a chain and sprocket drive arrangement. The invention may also be applied to other pedaled vehicles, such as a paddle boat, or to vehicles driven by a shaft rather than a drive chain.
A number of reciprocating foot-lever drives have been proposed for bicycles to be used in stead of the conventional crank and sprocket. Several of these are discussed in my earlier pat. U.S. Pat. No. 5,335,927. Typical of these is the bicycle drive system shown in Wheatley U.S. Pat. No. 584,200. In that case, there are foot levers that are pumped up and down to pull a drive chain back and forth over a sprocket, and a gear arrangement converts the back and forth motion to forward rotary motion to drive the rear wheel. However, the lever action used in these designs does not make optimal use of the muscle dynamics of the leg over the range of motion of the rider's leg. Also, there is no provision to recover energy from the top or bottom of a stroke to assist in the next stroke.